The invention pertains to a control for regulating the level or depth of an object in a liquid medium by means of an expandable working fluid. More particularly, the invention pertains to a control for regulating depth by heating and cooling a working fluid which is kept separated from the liquid medium by means of a displaceable barrier.
In the past, control of the operating depth of an underwater object, and the ascensions and descensions thereof, has usually required a system which changes the weight of the object, either by dropping ballast or by pumping water in and out. A ballast system requires storage of bulky and exhaustible weight. A system employing mechanical pumps requires a multiplicity of moving parts, producing reliability, and may be too noisy for certain military applications.
To overcome some of these disadvantages, some systems have been developed which include a chamber having ports or openings in the lower portion thereof, and a container for storing gas which is lighter than water under pressure. Upon launching such a system into a body of seawater or the like, seawater completely fills the chamber, causing the system to descend. To hydrodynamically stabilize the system at a selected depth, or to cause the system to ascend, the gas is released from the container into the chamber. The expansion of the gas forces some or all of the water out of the chamber through the ports, reducing the weight of the system.
A disadvantage of such a system lies in the possibility of a sudden reversal in the vertical orientation of the chamber, which would result in the escape of the gas through the ports, and a consequent flooding of the chamber. Also, the gas used in such a system is limited to a gas which is non-soluable in water, and once released from its container, the gas may not be recovered for reuse unless the system includes fairly elaborate gas compression or refrigeration equipment.